While recent winter weather storms may suggest otherwise, we are getting closer to the time that birds in this hemisphere begin their journey northward. Just like in the 1996 movie, Fly Away Home, last year’s crop of fledglings will begin their first return journey toward mating and nesting grounds.

However, a host of different variables can affect the success of these new populations year after year. Fly Away Home highlights how habitat loss might threaten migrating geese. But what about other, perhaps less obvious factors, such as those affecting bird breeding cycles?

EPA researchers have been working on a digital, easy-to-use model called the Markov Chain Nest Productivity Model, or MCnest, that estimates the impact of pesticide exposures on the reproductive success of bird populations.

MCnest combines existing avian (bird) toxicity test results, species life history information, and the timing of pesticide application(s) with breeding seasons to quantitatively estimate the potential impact of pesticide exposure on annual bird reproductive success.

Future MCnest results that indicate potential adverse affects on avian reproduction may be cited in Agency orders to regulate pesticide use under the Federal Insecticide Fungicide and Rodenticide Act (FIFRA), and in support of the Endangered Species Act (ESA). The ESA is administered by the U.S. Fish and Wildlife Service and the National Marine Fisheries Service, and requires federal agencies to ensure that any action they authorize won’t jeopardize listed threatened or endangered species.

Though MCnest is still in its early stages of development, work continues on a more advanced version that will improve exposure estimates and more realistically describe the length of avian breeding seasons. The researchers are also applying the concepts behind MCnest to develop a model for fish, and a similar model is possible for mammals.

As its capability grows to take in data about more species, MCnest can play a greater role in EPA’s approach to ecological risk assessment. In time, MCnest may provide a greater understanding of pesticides and their impact on wildlife and our environment.

Click here for more information on MCnest, data libraries and program instructions.

About the author: Thomas Landreth is a student services contractor working with EPA’s Office of Research and Development.

Editor’s note: for more information on McNest and other EPA ecosystems-related research, please see the latest edition of our newsletter, “Science Matters.”

Editor's Note:
The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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